<!DOCTYPE HTML>
<html>
    <head>
        <title>Example</title>
        <style>
            canvas {border: thin solid black}
            body > * {float:left;}
        </style>
    </head>
    <body>
        <canvas id="canvas" width="500" height="140">
            Your browser doesn't support the <code>canvas</code> element
        </canvas>
        <script>
            var ctx = document.getElementById("canvas").getContext("2d");

            ctx.fillStyle = "yellow";
            ctx.beginPath();
            ctx.rect(0, 0, 500, 140);
            ctx.fill();

            ctx.beginPath();
            ctx.rect(100, 20, 300, 100);
            ctx.clip();
          
            ctx.fillStyle = "red";
            ctx.beginPath();
            ctx.rect(0, 0, 500, 140);
            ctx.fill();
          
        </script>
    </body>
</html>
